The present invention relates to a switch device wherein an operation portion and a switch portion are free to be mounted to or dismounted from each other.
There have conventionally been known a switch device wherein the operation portion is free to be mounted to or dismounted from the switch portion (also referred to as a contact portion or a contacting portion) (see, for example, FIG. 8 in Japanese Unexamined Patent Publication No. 1-241723). Such a switch device includes a pushbutton switch wherein one or more pairs of contacts in the switch portion are separated off from each other (opened) in a state where the operation portion is dismounted from the switch portion. This type of switch is applied to, for example, an emergency stop pushbutton switch.
However, there may be a problem that if overcurrent or the like causes one or more pairs of contacts to be fused to each other, the contacts may be held in contact with each other even though the operation portion is dismounted from the switch portion. In a case where the switch device is applied to the emergency stop pushbutton switch, for example, the following problem may be encountered. If a pair of contacts are in contact with each other despite the operation portion dismounted from the switch portion, machine tools as an operation object is in an operative condition.
The invention has been accomplished to solve the above problem and has an object to provide a switch device which ensures that even if one pair of contacts are fused to each other, the contacts can positively be separated off from each other when the operation portion and the switch portion are dismounted from each other.